Glossary
ANSI Lumens — A standard for measuring the brightness. It is calculated by dividing a square meter image into nine equal rectangles,
measuring the lux (or brightness) reading at the center of each rectangle, and averaging these nine points.
Aspect Ratio — The most popular aspect ratio is 4:3 (4 by 3). Early television and computer video formats are in a 4:3 aspect ratio, which
means that the width of the image is 4/3 times the height. Brightness — The amount of light emitted from a display or projection display
or projection device. The brightness of projector is measured by ANSI lumens.
Color Temperature — The color appearance of white light. Low color temperature implies warmer (more yellow/red) light while high color
temperature implies a colder (more blue) light. The standard unit for color temperature is Kelvin (K).
Component Video — A method of delivering quality video in a format that consists of the luminance signal and two separate chrominance
signals and are defined as Y'Pb'Pr' for analog component and Y'Cb'Cr' for digital component. Component video is available on DVD players.
Composite Video — A video signal that combines the luma (brightness), chroma (color), burst (color reference), and sync (horizontal and
vertical synchronizing signals) into a signal waveform carried on a single wire pair. There are three kinds of formats, namely, NTSC, PAL,
and SECAM.
Compressed Resolution — If the input images are of higher resolution than the native resolution of the projector, the resulting image will
be scaled to fit the native resolution of the projector. The nature of compression in a digital device means that some image content is lost.
Contrast Ratio — Range of light and dark values in a picture, or the ratio between their maximum and minimum values. There are two
methods used by the projection industry to measure the ratio:
1 Full On/Off — measures the ratio of the light output of an all white image (full on) and the light output of an all black (full off) image.
2 ANSI — measures a pattern of 16 alternating black and white rectangles. The average light output from the white rectangles is
divided by the 7 Appendix: Glossary Glossary 53 average light output of the black rectangles to determine the ANSI contrast ratio.
Full On/Off contrast is always a larger number than ANSI contrast for the same projector.
dB — decibel — A unit used to express relative difference in power or intensity, usually between two acoustic or electric signals, equal to
ten times the common logarithm of the ratio of the two levels.
Diagonal Screen — A method of measuring the size of a screen or a projected image. It measures from one corner to the opposite corner.
A 9 FT high, 12 FT wide, screen has a diagonal of 15 FT. This document assumes that the diagonal dimensions are for the traditional 4:3
ratio of a computer image as per the example above.
DHCP — Dynamic Host Configuration Protocol — A network protocol that enables a server to automatically assign a TCP/IP address to a
device.
DLP® — Digital Light Processing™ — Reflective display technology developed by Texas Instruments, using small manipulated mirrors.
Light passing through a color filter is sent to the DLP mirrors which arrange the RGB colors into a picture projected onto screen, also
known as DMD.
DMD — Digital Micro-Mirror Device — Each DMD consists of thousands of tilting, microscopic aluminum alloy mirrors mounted on a
hidden yoke.
Focal Length — The distance from the surface of a lens to its focal point. Frequency — It is the rate of repetition in cycles per seconds of
electrical signals. Measured in Hz (Hertz).
HDCP — High-Bandwidth Digital-Content Protection — A specification developed by Intel™ Corporation to protect digital entertainment
across digital interface, such as DVI, HDMI.
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General
Weight and Dimensions
